/Engine/Source/Runtime/Engine/Classes/Kismet/BlueprintPathsLibrary.h
Optionally specify the character to replace invalid characters with
static [FString](API\Runtime\Core\Containers\FString) MakeValidFileName ( const [FString](API\Runtime\Core\Containers\FString) & InString, const [FString](API\Runtime\Core\Containers\FString) & InReplacementChar )